1. Field of the Invention
The present invention relates to an ink jet recording apparatus.
2. Related Background Art
Conventionally, there are ink jet recording apparatuses comprising recovery units for removing wet ink on the surface having an array of discharge ports caused by the ink mist occurring in discharging the ink from recording head, or the satellite ink occurring in refilling the ink, and the suction residual ink occurring in the recovery process such as the suction. This recovery apparatus is mainly comprised of a suction unit, for example, for forcing the ink to be discharged from the discharge port, and a wiping unit for wiping and cleaning the discharge port array face. In order to make the wiping (or cleaning) of the discharge port array face (hereinafter referred to as a discharge face) for an ink jet recording head having a plurality of discharge ports, for example, the wiping unit is constituted so as to wipe, in a scraping manner, the discharge port array face with a blade made of an elastic material placed directly against the discharge face while moving the blade relative to the ink jet recording head, to thereby clean the discharge port and its surrounding to maintain the stability of discharging.
Here, taking an example of ink deposition on the discharge face which may appear with the suction recovery, a conventional cleaning operation will be described with reference to FIG. 29.
A carriage 902 having an ink jet recording head 901 is carried on a main scan rail 903, and attached movably in a print direction (direction of arrow C). If the discharge port of the ink jet recording head 901 may be clogged, a holder 905 having gum caps 904 forming a closed system for the head is moved in a direction of arrow a by driving means, not shown, so that the gum caps 904 are brought into contact with the discharge face 901a of the ink jet recording head 901 and stopped at a position where the closed system is created. In this state, the suction recovery is performed via tubes 906 with a suction pump 907. The ink pulled out from the ink jet recording head 901 due to the suction is transported via a tube 908 into a waste ink processing member 909. After the suction recovery, the holder 905 having the gum caps 904 are retracted in the direction of arrow b by the driving means. At this time, ink droplets I pulled out from nozzles may remain on the discharge port 901a of the ink jet recording head 901. The carriage 902 having the ink jet recording head 901 is moved in the direction of arrow C [(A) state], the wiping for the discharge port 901a is performed with a gum blade 910 carried by a blade holder 911 [(B) state], whereby ink droplets I on the discharge face 901 are removed from the discharge face 901a.
However, to improve the cleaning performance for the discharge face of ink jet recording apparatus and stabilize the discharge characteristics in a long term service, there are conventionally the following problems, particularly in a color recording apparatus having a cartridge-type head or a plurality of heads.
The first problem is that the ink accumulating in a gap between the head and the carriage may cause an adverse effect.
That is, there is a fear that in wiping ink droplets remaining on the discharge face of head after the print or suction, the ink may enter the gap between the head and the carriage, as shown in the (B) state of FIG. 29, and the accumulating ink may drip after a long term of service or scatter away due to the engagement with the blade, thereby polluting a print face or back face of print sheet. Also, there is a further fear that when the accumulating ink contains dust or thickens, it may be retransferred onto the blade in cleaning to enter the discharge ports of the head downstream in the wiping direction, thereby causing a print deflection or undischarge. Further, the undischarge owing to intermixed dust or thickened ink may exert the adverse effect on energy generating elements for use in discharging the ink (e.g., scorching of heat generating element).
Second, there is a problem of the adverse effect due to the swept ink in wiping.
That is, most recent ink jet recording heads have a plurality of discharge ports arranged, so that the wiping is carried out with a wider blade than a discharge port array range. However, a considerably greater amount of ink droplets may remain if the number of discharge ports increases, and this ink tends to remain on the discharge port array facing downstream of the blade in the wiping direction. If ink droplets remaining on this portion may be fixed in a long term service, an failure of enclosing a cap portion may occur. If this occurs, the print deflection or undischarge is likely to occur due to capping failure with the non-used recording head, and further a failure of suction or wiping may arise.
Further, thirdly, with the apparatus having a plurality of heads corresponding to the inks differing in the color tone, if the wiping is made for such heads in sequence, there is a fear that the adhering ink (wet ink) to the discharge face in the vicinity of discharge ports of the head upstream of the wiping may be transferred onto the blade in wiping after the ink suction or print, and the inks different in the color may enter discharge ports of the head downstream thereof. Thus, the color mixture of different ink colors or the undischarge failure due to the mixture of different components may occur.
Further, fourthly, there is a problem associated with the exchange of a cartridge type head. That is, when the cartridge type head is exchanged, the operator may dirty his hands or clothes with the exchange of the head if the head is polluted with the adhering ink for the above reason.
On the other hand, in order to make the recording at high precision or with high quality, it is required to reduce the dispersion between product heads as least as possible. To meet this requirement, a method has been proposed in which data concerning the uneven density for each head is measured in fabricating the ink jet head, and the correction data for correcting the driving condition of head or various characteristics for the image processing are prewritten into a semiconductor memory (e.g., ROM) which is mounted on the product, thereby controlling the discharge and improving the previous problem.
Though the cleaning of discharge ports is an important factor for improving the recording quality in the ink jet recording as previously described, the wiped out ink may be scattered away with the restoring force of a cleaning blade due to its elasticity which may be separated from discharge port formation face, in cleaning the discharge port formation face with the wiping of the cleaning blade. Thus, there is a fear that the apparatus may be internally polluted with such scattered ink, or the ink may flow around the side face of head, and stick to the memory device provided on the head, causing a malfunction or breakdown.